SpudFiles

My school is having a science fair and i am going to use spud guns in it. In the science fair you have to be able to preform an experiment and have a problem. you have to solve that problem by using the scienctific method.(State hypothiseis, create experiment to test hypothiseis, collect data, analyze data, and come up with a conclusion)

wondering about any hypothiseis's you can come up with to help me out or experiments to do

How much fuel is needed to propel a spud 100 yards, there is your question/problem. Method- combustion of gaseous fuel (chemical energy).
Hypothisis- is it possible to propel a spud to a distance of 100yards using a gaseous fuel? (no brainer). You could make a chart showing the reaction at combustion and such.
You will win for sure if you let the judges fire it

something about the stoicheometric <spelling? percentage blah blah blah in a combustion type situation heck i don't know something like that

well, unless your in chem it going to be hard to do the stoichiometric ratios

If you want a solid experiment, you must test only one variable at a time. Are you "shooting" (pun intended) to win, to have fun, and/or to get a good grade? Not to brag, but I brought home gold at the PA state level fair, so I know what they look for.

First off, you need to use a gun capable of a consistant range. This either means a pnuematic or a metered combustion. You also need uniform size and weight ammo (unless that is your variable). This means golf balls, paintballs, tennis balls, but not potatos.

Also, if you don't understand what I am refering to, read the spudfiles wiki.

Here are some ideas:

How does the fuel to air ratio affect range?
How does rifling affect accuracy?
What type of potato flies the best?
How effective are different types of silencers?
How does the barrel to chamber ratio affect preformance?
How do fins affect accuracy and range?
How much pressure does propane combustion generate at defferent ratios?


For these ideas, you will need varrying amounts of time, resorces, knolage and skill, so pick something that you know you can do.

if youre doing it for school i suggest you use a pneumatic as schools dont seem to like combustion launchers and see them as a danger.

haha i am building a tennis ball launcher for my gay invention convention contest.



sweet

thanks guys i can do just about anything i need to i actually am not that new to spud guns one thing i waned to know more about is the barrel chamber ratios. thouht they would seem smart and sciencetific. i think you guys have almost nailed what i want also how would i measure pressure in a combustion. i was going to also compare combust to pneumat. (distances, fps, also might make ballistics jelly) oh and my teacher said i could do aaannnyyy thing i wanted aslong as i could make an experiment out of it. Yay this gives me a reason to complete my gb sniper and make a metered propane. more ideas welcome. also all of my experiments have to have a control in them srry for the late notice but just remembered. if you could tell me the controls in those experiment would be even more help thxs alot

Combustion of C3H8 in air at 1atm won't produce more than 120 psig of hot gases in optimum conditions. The "valve" in a combustion is fairly slow compared to a piston valve. There is no comparison. If you build an optimised burst disk metered combustion and a burst disk pneumatic of the same dimensions running on 100 psi helium, performance would be comparable, but would still angle towards the pneumatic due to heat loss in the combustion.

C:B ratios have already been figured out for pneumatics and combustions, so unless you want to experiment on hybrids with a very accurate setup, then C:B testing is rather pointless.

What you should try is to test what sort of acceleration forces various projectiles can withstand before they break down in the barrel. This could be an excuse to build a really monstrous launcher. The " BB gun" that I'm starting now should put slightly over 12 000 Gs of acceleration on its standard projectiles (24mm steel Ball Bearings ). Test what kind of acceleration a potato can withstand before being mashed/vaporised.

And if you want this to sound smart and scientific, you may first want to learn how to spell "scientific". (Or "thought" for that matter )

i n o i hab bab pell in buh chan hep it. No i just cant type at all that s a good i dead though i could build the ultra mega monster i was thinking about oh and when i said cb ratios i meant what they mean and how to use them or come up with them.

(actually on my sat 9s i had the highest average you could get in all subjects. 9.5, my moms a teacher she know all about this thing called school.

I personally agree with DYI's idea of testing the durability of different objects fired out of a cannon.

(and Maniac, please don't go off on a tangent of trying to boast about what you have. I too have a mother who teaches AP Chemistry, however, that doesn't really mean anything in regards to this subject. Don't take this the wrong way, but it irritates me when people do things like that.)

btw don't call it a gun. I had to change the name to "pneumatic accelerator" or else they wouldn't have let me enter

I got one for you. How do you make mash potatos with a few tubes of PVC and a brick wall

I saw a kid do "How does the barrel to chamber ratio affect performance?" and he got like 3rd place. So I guess I would reccomend that.

Do anything that you could relate to math. And relate it to some big hotspot in the news. For some reason people appreciate that in todays society.